I have not performed this mod on the Pantera but had another muscle car where the caster was maxed out. The effect is like a shopping cart. By having the wheel raked back, high speed stability is improved in a straight line and the wheel wants to self-center. The effect is a more stable run in straight sections. The downside is that low speed steering is much heavier. So turning the wheel while parking would be harder.
Like all thing, it depends on what you are trying to accomplish. For fast driving the change might be worth the effort. Otherwise, it is possible to add a few degrees of caster, by aligning the wheels differently. This involves moving all of the shims on the upper ball joint to one side (Shims to the front of the car).
If I were to re-build my front end, I would consider the bushings provided the cost is not wildly more then standard bushings.
